Radio transmission apparatus, and radio transmission method

ABSTRACT

Provided is a communication device, which is enabled to improve the throughput of a communication system by reducing the difference of a transmission power between an SCCH and an SDCH thereby to satisfy the required quality of a PAPR. In this device, an MCS selection unit ( 111 ) of a transmission unit ( 110 ) decides, with reference to a CQI lookup table, an MCS pattern (MCS1) of the SDCH, an MCS pattern (MCS2) of the SCCH and information (multiplex information) on multiplex positions on the time axes of those two channels, on the basis of the CQI information. On the basis of the MCS2 and the MCS1, encoding modulation units ( 112  and  113 ) perform encoding and modulating operations. According to the multiplex information, a channel multiplexing unit ( 114 ) time-division multiplexes the SCCH and the SDCH thereby to generate a transmission signal.

TECHNICAL FIELD

The present invention relates to a radio transmitting apparatus andradio transmission method used in a communication system employing anadaptive modulation scheme.

BACKGROUND ART

Currently, in uplink of 3GPP RAN LTE (Long Term Evolution), to realize alow PAPR (Peak to Average Power Ratio), attention is focused on singlecarrier transmission. Further, a scheme is studied of selecting an MCS(Modulation and Coding Scheme) pattern per user according to a CQI(Channel Quality Indicator) of the user and performing adaptivemodulation and coding (AMC) to obtain high throughput (for example, seeNon-Patent Document 1).

Further, to perform adaptive modulation and coding, a technique is knownof multiplexing a control channel required for decoding a data channelwith the data channel and transmitting the multiplexed channel (forexample, see Non-Patent Document 2). Non-Patent Document 2 defines anSDCH (Scheduled Data Channel) as a data channel and defines an SCCH(Scheduled Control Channel) as a control channel.

Non-Patent Document 1: 3GPP TS25.211 v6.5.0, June, 2005

Non-Patent Document 2: 3GPP TSG RANI R1-050679, June 2005

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

To focus on a subframe format studied in 3GPP RAN LTE, when a pluralityof channels such as an SCCH and SDCH are multiplexed, a possible frameconfiguration is where a pilot channel is on an SB (Short Block) and theSCCH and SDCH are time division multiplexed on an LB (Long Block). FIGS.1 and 2 show specific examples of frame configurations where the SCCHand SDCH are time division multiplexed.

FIGS. 1 and 2 also show transmission power of the SCCH and SDCH. Asshown in these figures, cases occur where the difference of transmissionpower between the SCCH and the SDCH increases due to the followingreasons.

As the MCS for the SCCH, a spreading factor, modulation scheme andcoding rate where the required CNR is low, is commonly used by all userssuch that even a user in a poor reception environment can satisfyrequired quality. That is, in 3GPP RAN LTE, adaptive modulation andcoding is performed, and so the MCS pattern for the SDCH changesvariously, while the MCS pattern for the SCCH (not includingtransmission power) is fixed.

However, to reduce level fluctuation errors due to fading and ensurerequired quality of the SCCH, the transmission power for the SCCH iscontrolled such that the transmission power is changed per useraccording to the received power of each user.

That is, the transmission power for the SCCH changes through thetransmission power control, while the transmission power for the SDCHchanges through adaptive modulation and coding, and therefore thetransmission power for the SCCH and the transmission power for the SDCHchange independently from each other. Therefore, as shown in FIG. 1, thetransmission power for the SCCH may be higher than the transmissionpower for the SDCH, or, as shown in FIG. 2, the transmission power forthe SCCH may be lower than the transmission power for the SDCH.

In both cases, the difference of transmission power between the SCCH andthe SDCH becomes large. Consequently, the PAPR for the transmissionsignal including these two channels shows a high value, and so it isnecessary to provide enough back-off of the transmission amplifier anddecrease total transmission power upon transmission so as not to causedistortion in the transmission signal. As a result, the required qualityof these two channels cannot be satisfied and communication systemthroughput decreases.

It is therefore an object of the present invention to provide a radiotransmitting apparatus and radio transmission method capable ofimproving communication system throughput by making the difference oftransmission power between the SCCH and the SDCH small, suppressing anincrease of the PAPR, and making it easier to satisfy required qualityof the two channels.

Means for Solving the Problem

The radio transmitting apparatus of the present invention determines anMCS of the transmission signal based on a CQI reported from acommunicating party and adopts a configuration including: a determiningsection that determines an MCS for a data channel based on the CQIreported from the communicating party and determines an MCS for acontrol channel based on the same CQI; and a transmitting section thattransmits the transmission signal including the data channel and thecontrol channel.

Advantageous Effect of the Invention

According to the present invention, it is possible to suppress anincrease of the PAPR, make it easier to satisfy required quality of thetwo channels and improve communication system throughput.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a specific example of a frame configuration where an SCCHand an SDCH are time division multiplexed;

FIG. 2 shows another specific example of the frame configuration wherethe SCCH and the SDCH are time division multiplexed;

FIG. 3 is a block diagram showing a main configuration of acommunication apparatus according to Embodiment 1;

FIG. 4 is a block diagram showing a main internal configuration of anMCS selecting section according to Embodiment 1;

FIG. 5 shows an example of content of a CQI look-up table according toEmbodiment 1;

FIG. 6 shows an example of a frame format of a transmission signal wherean SCCH and an SDCH are multiplexed;

FIG. 7 is a block diagram showing a main configuration of acommunication apparatus according to Embodiment 2;

FIG. 8 is a block diagram showing a main internal configuration of anMCS selecting section according to Embodiment 2;

FIG. 9 shows an example of content of a CQI look-up table according toEmbodiment 2;

FIG. 10 is a block diagram showing a main configuration of acommunication apparatus according to Embodiment 3;

FIG. 11 is a block diagram showing a main internal configuration of adecoding section according to Embodiment 3;

FIG. 12 shows an example of a format of a signal where CQI informationand a CQI offset command are multiplexed;

FIG. 13 is a block diagram showing a main internal configuration of anMCS selecting section according to Embodiment 3;

FIG. 14 specifically illustrates how a CQI is actually corrected by theCQI offset command; and

FIG. 15 is a block diagram showing a main configuration of acommunication apparatus provided with a radio receiving apparatusaccording to Embodiment 3.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings. Here, a case will bedescribed where the DFT-s-OFDM (Discrete FourierTransform-Spread-Orthogonal Frequency Division Multiplex) scheme, thatis, a single carrier communication scheme is employed as a communicationscheme.

Embodiment 1

FIG. 3 is a block diagram showing a main configuration of acommunication apparatus provided with a radio transmitting apparatusaccording to Embodiment 1 of the present invention.

This communication apparatus is mainly configured with receiving section100 and transmitting section 110. Receiving section 100 has radioreceiving section 101, CP removing section 102, FFT section 103,demodulating section 104, decoding section 105 and channel estimatingsection 106, and transmitting section 110 has MCS selecting section 111,encoding and modulating sections 112 and 113, channel multiplexingsection 114, DFT-s-OFDM section 115, CP adding section 116 and radiotransmitting section 117.

The sections of the above-described communication apparatus perform thefollowing operations.

Radio receiving section 101 of receiving section 100 converts the signalreceived through antenna 120 to a baseband signal and outputs thebaseband signal to CP removing section 102. CP removing section 102performs processing of removing a CP (Cyclic Prefix) part of thebaseband signal outputted from radio receiving section 101, and outputsthe obtained signal to FFT section 103. FFT section 103 performs a fastFourier transform (FFT) on the time domain signal outputted from CPremoving section 102, and outputs the obtained frequency domain signalto demodulating section 104 and channel estimating section 106. Channelestimating section 106 estimates channel environment of the receivedsignal using a pilot signal included in the signal outputted from FFTsection 103, and outputs the estimated result to demodulating section104. Demodulating section 104 performs channel compensation on a signalwhere control information such as a pilot signal is removed (datainformation) out of the received signal subjected to the Fouriertransform processing at FFT section 103, based on the estimated resultof the channel environment outputted from channel estimating section106. Further, demodulating section 104 performs demodulating processingon the signal subjected to channel compensation based on the same MCS asused in the radio transmitting apparatus, that is, the same modulationscheme, coding rate, and the like as the radio transmitting apparatus,and outputs the result to decoding section 105. Decoding section 105performs error correction on the demodulated signal and extracts aninformation data sequence and CQI information from the received signal.The CQI information is outputted to MCS selecting section 111.

In the meantime, MCS selecting section 111 of transmitting section 110determines the MCS pattern of an SDCH (MCS 1), the MCS pattern of anSCCH (MCS 2) and information relating to the multiplexing position ofthese two channels in the time domain (multiplexing information), basedon the CQI information outputted from decoding section 105 withreference to a CQI look-up table described later. MCS 1 is outputted toencoding and modulating section 113, MCS 2 is outputted to encoding andmodulating section 112, and the multiplexing information is outputted tochannel multiplexing section 114.

Encoding and modulating section 113 performs encoding and modulatingprocessing on inputted user data (transmission data sequence) based onthe MCS pattern (MCS 1) outputted from MCS selecting section 111, andgenerates transmission data for the SDCH and an IR pattern used uponencoding. The transmission data for the SDCH is outputted to channelmultiplexing section 114, and the IR pattern is outputted to encodingand modulating section 112.

Encoding and modulating section 112 performs encoding and modulatingprocessing on control information such as the IR pattern outputted fromencoding and modulating section 113, based on the MCS pattern outputtedfrom MCS selecting section 111, and generates transmission data for theSCCH. The generated transmission data for the SCCH is outputted tochannel multiplexing section 114.

Channel multiplexing section 114 time-division multiplexes thetransmission data for the SCCH and SDCH outputted from encoding andmodulating sections 112 and 113 according to the multiplexinginformation outputted from MCS selecting section 111. The multiplexedtransmission data is outputted to DFT-s-OFDM section 115.

DFT-s-OFDM section 115 performs a discrete Fourier transform (DFT) onthe transmission data outputted from channel multiplexing section 114,performs time-frequency conversion on time-series data, and obtains afrequency domain signal. After mapping the frequency domain signal ontransmission subcarriers, DFT-s-OFDM section 115 performs inverse fastFourier transform (IFFT) processing and converts the frequency domainsignal to a time domain signal. The obtained time domain signal isoutputted to CP adding section 116.

CP adding section 116 adds a CP per transmission data block byduplicating data at the tail of a block per transmission data blockoutputted from DFT-s-OFDM section 115 and inserting the duplicated datainto the beginning of the block, and outputs the result to radiotransmitting section 117.

Radio transmitting section 117 converts the baseband signal outputtedfrom CP adding section 116 to a radio frequency band, and transmits theresult through antenna 120.

FIG. 4 is a block diagram showing the main internal configuration of MCSselecting section 111. Information selecting section 121 determines MCS1 for the SDCH, MCS 2 for the SCCH and multiplexing information based onthe inputted CQI with reference to CQI look-up table 122 shown in FIG.5.

FIG. 5 shows an example of content of CQI look-up table 122 as describedabove. Here, a case will be described as an example where modulationschemes of BPSK (Binary Phase Shift Keying), QPSK (Quadrature PhaseShift Keying) 16 QAM (Quadrature Amplitude Modulation) and 64 QAM areemployed, coding rates of ⅓, ½, ⅔, ¾, ⅚ and ⅞ are employed, and, onlyfor BPSK, repetition factors (RFs) of 1, 2, 4, 8, 16 and 32 areemployed.

For example, when CQI=7, information selecting section 121 selects amodulation scheme of QPSK, a coding rate of ¾ and a repetition factor of1 for the SDCH with reference to CQI look-up table 122, and outputsthese collectively as MCS 1. Further, information selecting section 121uses the same CQI=7, selects a modulation scheme of QPSK, a coding rateof ⅓ and a repetition factor of 1 matching CQI=7 for the SCCH, andoutputs these as MCS 2. In this way, from FIG. 5, how MCS 1 for the SDCHand MCS 2 for the SCCH are set in association with each other for eachCQI, can be understood.

In this CQI look-up table 122, MCS 2 for the SCCH is set using thefollowing method according to MCS 1 for the SDCH set on a per CQI basis.

First, the MCS for the SDCH is determined for each CQI. Next, an averagetransmission rate of the SDCH is calculated per CQI, and the MCS for theSCCH is determined using the following determination method. That is, byassuming that the average transmission rate of the SDCH is A, the numberof symbols of the SDCH is B, the PER (Packet Error Rate) when MCS 1 (forexample, QPSK and R=½) is selected for the SCCH is C, the PER when MCS 2(for example, QPSK and R=⅓) is selected for the SCCH is D, and thedifference between the number of symbols of the SCCH (MCS 1) and thenumber of symbols of the SCCH (MCS 2) is E, and, by comparing “A×(1−C)”with “A×(1−D)×(E+B)/B,” the MCS having the greater value, that is theMCS having the higher transmission rate is made the MCS for the SCCH. Inaddition, both (1−C) and (1−D) represent a rate of SDCH transmissionrate decrease due to SCCH reception errors, and (E+B)/B represents arate of SDCH transmission rate increase when SCCH resources are madeSDCH resources.

In other words, in CQI look-up table 122, MCS 1 and MCS 2 are set suchthat the PAPRs for the SCCH and SDCH remain within the range of theassumed PAPR and a transmission rate of the SCCH and SDCH becomes amaximum.

Further, in FIG. 5, multiplexing information A to P is information asdescribed below. FIG. 6 shows an example of a frame format of atransmission signal where an SCCH and an SDCH are multiplexed.

This figure shows a frame format of the transmission signal when the CQIis different, for example, a transmission signal when the CQI is 2,shown in the upper part, and a transmission signal when the CQI is 9,shown in the lower part. In this way, when the SCCH is mapped at thebeginning and the SDCH is mapped following the SCCH, the number oftransmission data for the SCCH, that is, the number of SCCH symbols,changes according to CQIs, and so the starting position of the SDCHchanges. Therefore, in this embodiment, a plurality of types ofinformation showing the starting position of the SDCH are set by CQIlook-up table 122 as information (multiplexing information) relating tothe multiplexing position of the two channels in the time domain.Channel multiplexing section 114 acquires multiplexing information foreach CQI set in CQI look-up table 122 through information selectingsection 122 in MCS selecting section 111, and multiplexes the SCCH andthe SDCH using this multiplexing information.

Here, the information amount before encoding which is transmitted usingthe SCCH, is a fixed rate regardless of the MCS for the SDCH. Therefore,particularly, when the CQI is high, more SCCH transmission symbols afterencoding and modulation can be reduced than the case where the CQI islow, and the SCCH symbol resources can be used as SDCH symbol resources(resources of a diagonal part in FIG. 6), so that it is possible tofurther improve SDCH throughput.

In addition, CQI look-up table 122 is also provided to a radio receivingapparatus supporting the radio transmitting apparatus according to thisembodiment, and so the information set in CQI look-up table 122 is knownbetween the transmitting side and the receiving side.

In this way, according to this embodiment, in single carriertransmission where a plurality of channels are multiplexed, the MCSpattern for each channel is set in a CQI table (CQI look-up table 122)according to CQIs such that the difference of transmission power betweenthe SCCH and the SDCH remains within a predetermined range. The radiotransmitting apparatus according to this embodiment acquires MCSpatterns for channels of the SCCH and the SDCH according to CQIs withreference to this CQI table, performs adaptive modulation and codingbased on these MCS patterns and generates a transmission signal. By thismeans, it is possible to maintain a low PAPR of the transmission signal,and so it is more likely to satisfy required quality of the twochannels. That is, it is possible to improve communication systemthroughput.

Further, according to this embodiment, by changing the MCS pattern forthe SCCH, the required quality for the SCCH is more likely to besatisfied, so that transmission power control is not required in theSCCH. Transmission power does not fluctuate independently from eachother among a plurality of channels. Therefore, by maintaining a lowPAPR, the two channels are more likely to satisfy the required quality,so that it is possible to improve communication system throughput.

Further, according to this embodiment, the SCCH and the SDCH are set inthe same CQI table so as to correspond to the same CQI, and this CQItable is shared between the transmitting side and the receiving side. Bythis means, the radio receiving apparatus supporting the radiotransmitting apparatus according to this embodiment can acquireinformation relating to the MCS for the SCCH with reference to the CQItable shared between the transmitting side and the receiving side basedon the reported CQI, and does not need to separately acquire informationrelating to the MCS for the SCCH from the radio transmitting apparatusaccording to this embodiment. That is, new signaling is not required.

In this embodiment, the SCCH and the SDCH are shown as examples of aplurality of channels subjected to time division multiplexing, but thechannels the present invention is directed to are not limited to these,and, for example, the present invention may also be directed to three ormore channels having different required quality or may be directed tochannels employing different coding schemes. Further, an example hasbeen described where time division multiplexing is performed on theSCCH, followed by the SDCH, but this is by no means limiting, and, forexample, time division multiplexing is performed on the SDCH, followedby the SCCH.

Still further, a case has been described with this embodiment where CQIlook-up table 122 is structured such that different MCS patterns and thelike are set for different CQIs, but CQI look-up table 122 may bestructured such that the same MCS pattern is set for different CQIs.

Further, CQI look-up table 122 may be structured such that different MCSpatterns are set per bandwidth to be used.

Further, in this embodiment, CQI look-up table 122 may be structuredsuch that the SCCH and the SDCH are interleaved in a sub-frame in thetime domain.

Still further, in this embodiment, CQI look-up table 122 may bestructured such that the above-described MCS and the like are added andthe number of pilot symbols and the multiplexing position of this pilotare set.

Embodiment 2

FIG. 7 is a block diagram showing the main configuration of thecommunication apparatus provided with the radio transmitting apparatusaccording to Embodiment 2 of the present invention. This communicationapparatus has a basic configuration similar to the communicationapparatus described in Embodiment 1 (see FIG. 3), and the samecomponents will be assigned the same reference numerals without furtherexplanations.

The communication apparatus according to this embodiment further haspower difference setting section 201 and power controlling section 202,and the transmission power of the SCCH is controlled. However,predetermined limits are placed on the difference of transmission powerbetween the SCCH and the SDCH, and so transmission power can satisfy therequired PAPR even if the transmission power is controlled. This isdifferent from Embodiment 1.

FIG. 8 is a block diagram showing the main internal configuration of MCSselecting section 111 a.

MCS selecting section 111 a performs the same basic operations as MCSselecting section 111 described in Embodiment 1, but is different fromEmbodiment 1 in that MCS selecting section 111 a outputs (the settingvalue of) transmission power and transmission power differenceinformation in addition to information of MCS 1 for the SDCH and thelike. Therefore, the same reference numerals as MCS selecting section111 are assigned, and, to distinguish the MCS selecting section fromEmbodiment 1, the letter “a” is assigned to the reference numeral 111.To other components, letters are added for the same reason.

FIG. 9 shows an example of content of CQI look-up table 122 a.

In CQI look-up table 122 a, when the CQI level remains within the rangeof 1 to 8, that is, when the CQI level is low, transmission power is setwith the same value of 27 dB. On the other hand, when the CQI levelremains within the range of 9 to 16, that is, when the CQI level ishigh, the transmission power is set with different values of 19 to 26dB, according to the CQI level.

Further, the transmission power difference is set with 0 dB when themodulation scheme for the SDCH and the modulation scheme for the SCCHare the same, that is, the transmission power for the both channels isset with the same value. On the other hand, when the modulation schemefor the SDCH is different from the modulation scheme for the SCCH, thetransmission power difference is set with values other than 0 dB. Here,although the transmission power difference is set with values other than0 dB, the value is not unlimited, and values which have the range within0.5 to 3.5 dB and which satisfy the following conditions are set. Thereasons for this include, if modulation schemes are different, PAPRsbecome different in principle, and so, when the modulation scheme forthe SDCH is different from the modulation scheme for the SCCH, even ifthe difference of PAPR in principle is set as a power difference, theoverall PAPR does not increase, and throughput of the channel using themodulation scheme having the lower PAPR can be improved.

Further, when CQI=16, for example, the modulation scheme for the SDCH is64 QAM, while the modulation scheme for the SCCH is QPSK, and there is agreat difference in transmission rate and error robustness (which have atrade-off relationship) between these two modulation schemes. In thiscase, when the transmission power for the SDCH having low errorrobustness is set low by transmission power control, the PAPR mayincrease to an extent which does not cause distortion by a transmissionamplifier, and the transmission power difference is set a maximum of 3.5dB, such that transmission power for the SCCH having high errorrobustness is set as high as possible to make SCCH errors less likely.

In this way, according to this embodiment, when the modulation schemesfor a plurality of channels are different, the transmission powerdifference is set per channel so as not to increase the PAPR. By thismeans, when there is some PAPR difference among the plurality ofchannels, it is possible to maintain a low PAPR and improve throughputfor each channel.

Further, according to this embodiment, when the CQI level is low,transmission power is set with a constant value. That is, when the CQIlevel is low, transmission power control is not performed. By thismeans, it is possible to maintain a low PAPR and improve throughput foreach channel.

Embodiment 3

FIG. 10 is a block diagram showing the main configuration of thecommunication apparatus provided with the radio transmitting apparatusaccording to Embodiment 3 of the present invention. This communicationapparatus also has the basic configuration similar to the communicationapparatus described in Embodiment 1, and the same components will beassigned the same reference numerals without further explanations.

The communication apparatus according to this embodiment receives a CQIand a CQI offset command and corrects the finally selected MCS for thetransmission signal by correcting the CQI level for the SCCH or theSDCH. To be more specific, decoding section 105 b extracts a transmittedinformation data sequence from a demodulated received data sequence,extracts CQI information and CQI offset command information, and outputsthe extracted data sequence and information to MCS selecting section 111b.

FIG. 11 is a block diagram showing the main internal configuration ofdecoding section 105 b.

Channel dividing section 301 divides the demodulated data sequence intothe data channel and the control channel, and outputs these channels.Error correction and decoding section 302 performs error correction anddecoding on the data channel outputted from channel dividing section301, and outputs the obtained information data, that is, user data. Onthe other hand, error correction and decoding section 303 performs errorcorrection and decoding on the control channel outputted from channeldividing section 301, and outputs the obtained control data to controldata dividing section 304. Control data dividing section 304 extractsCQI information and a CQI offset command from the control channel basedon predetermined control data mapping information, and outputs theextracted information and command to MCS selecting section 111 b.

FIG. 12 shows an example of a signal format where CQI information and aCQI offset command to be inputted to control data dividing section 304are multiplexed.

FIG. 13 is a block diagram showing the main internal configuration ofMCS selecting section 111 b.

Information selecting section 121 b first determines MCS 1 for the SDCHaccording to the CQI information with reference to CQI look-up table 122described in Embodiment 1. Information selecting section 121 b thenacquires a CQI offset command with reference to CQI look-up table 122 inthe same way. This CQI offset command is specifically “−1” or “0 (nooffset).” Information selecting section 121 b adds this CQI offsetcommand to the CQI information, and determines MCS 2 for the SCCHaccording to new corrected CQI information. The multiplexing position isdetermined when MCS 2 is determined, and so MCS 1, MCS 2 andmultiplexing information are outputted.

When the CQI offset command is “−1,” it means that the error robustnessof the CQI improves by one step. In this way, by making the offsetdegree of the CQI one step, the required PAPR does not change. CQIlook-up table 122 originally sets the MCS patterns for the SCCH and theSDCH that satisfy the required PAPR. Therefore, the required PAPR mustbe satisfied by selecting the MCS pattern for each channel according tothis CQI table, and so, MCS patterns that go significantly outside thisCQI table should not be selected. The offset degree of the CQI is madeone step in order to minimize the offset degree.

FIG. 14 specifically illustrates how the CQI is actually corrected bythe above-described CQI offset command. In addition, the CQI table shownhere is the same as that shown in Embodiment 1 (see FIG. 5).

For example, when CQI=8 and CQI offset command=−1, QPSK, R=⅚ and RF=1are first selected as MCS 1 for the SDCH. Next, CQI=8 in MCS 2 for theSCCH, and so CQI offset command=−1 is added, and the CQI is therebycorrected as CQI=7. Therefore, corrected MCS 2 for the SCCH includesQPSK, R=⅓ and RF=1 (diagonal part in FIG. 14), and has a coding ratewith high error robustness.

In addition, the above-described CQI offset command is reported with theCQI from the radio receiving apparatus supporting the radio transmittingapparatus according to this embodiment. The method of generating a CQIoffset command at the radio receiving apparatus will be described below.

FIG. 15 is a block diagram showing the main configuration of thecommunication apparatus provided with the above-described radioreceiving apparatus. In addition, radio receiving section 151, CPremoving section 152, FFT section 153, channel estimating section 156,encoding and modulating sections 162 and 163, channel multiplexingsection 164, DFT-s-OFDM section 165, CP adding section 166 and radiotransmitting section 167 employ the same configuration as radioreceiving section 101, CP removing section 102, FFT section 103, channelestimating section 106, encoding and modulating sections 112 and 13,channel multiplexing section 114, DFT-s-OFDM section 115, CP addingsection 116 and radio transmitting section 117 of the communicationapparatus described in Embodiment 1, respectively, and so theexplanations thereof will be omitted.

Frequency equalizing section 171 performs frequency equalizingprocessing on the signal outputted from FFT section 153, and outputs theresult to DFT section 172.

DFT section 172 performs discrete Fourier transform processing on thesignal outputted from frequency equalizing section 171, and outputs theresult to channel demultiplexing section 173.

Channel demultiplexing section 173 demultiplexes the signal outputtedfrom DFT section 172 into an SDCH signal and an SCCH signal, outputs theSDCH signal to decoding section 174, and outputs the SCCH signal todecoding section 175.

Decoding sections 174 and 175 decode the SDCH and SCCH outputted fromchannel demultiplexing section 173 and outputs the results.

CQI offset command calculating section 176 calculates a CQI offsetcommand based on a mean error rate of the received SCCH, and outputs theCQI offset command to encoding and modulating section 162 oftransmitting section 160. To be more specific, when the mean error rateof the SCCH is equal to or greater than a predetermined threshold, thatis, when the mean error rate of the SCCH does not satisfy the requiredquality, “−1” is set for the CQI offset command, and, when the meanerror rate of the SCCH is less than the predetermined threshold, “0” isset for the CQI offset command.

CQI calculating section 177 calculates a CQI to report based on thereceived level of the received pilot signal, noise power andinterference power, and outputs the CQI to encoding and modulatingsection 162 of transmitting section 160.

In this way, according to this embodiment, the CQI level for one of theSCCH and the SDCH is corrected based on the CQI offset command. By thismeans, when the required quality for one of the channels cannot besatisfied, by correcting the CQI for this channel, an MCS pattern lowerthan the required CNR can be used, and throughput can be improved foreach channel.

Although a case has been described above as an example in thisembodiment where the CQI offset command includes two values of “−1” and“0,” the CQI offset command includes three values of “−1,” “0” and “1”or more than three values.

Further, although an example has been described with this embodimentwhere the CQI offset degree is one step (when the CQI offset command is“−1”), the CQI offset degree may be two steps or more using other valuessuch as a CQI offset command of “−2” within a range where the PAPR doesnot change.

Embodiments of the present invention have been described.

The radio transmitting apparatus and radio transmission method accordingto the present invention are not limited to the above-describedembodiments, and can be implemented with various modifications. Forexample, the embodiments can be combined as appropriate and implemented.

The radio transmitting apparatus according to the present invention canbe provided to a mobile station apparatus and base station apparatus ina mobile communication system, and it is thereby possible to provide amobile station apparatus, base station apparatus and mobilecommunication system having the same operation effects as describedabove.

Further, the radio transmitting apparatus and radio transmission methodaccording to the present invention can be used in the communicationsystem employing communication schemes other than single carriercommunication.

In addition, the SCCH in the above-described embodiments may be a DACCH(Data Associated Control Channel) or a DNACCH (Data Non-AssociatedControl Channel).

Further, although the present invention is configured with hardware asan example, the present invention can also be implemented with software.For example, the functions similar to those of the radio transmittingapparatus according to the present invention can be realized bydescribing an algorithm of the radio transmission method according tothe present invention in a programming language, storing this program ina memory and causing an information processing section to execute theprogram.

Each function block used to explain the above-described embodiments maybe typically implemented as an LSI constituted by an integrated circuit.These may be individual chips or may be partially or totally containedon a single chip.

Furthermore, here, each function block is described as an LSI, but thismay also be referred to as “IC”, “system LSI”, “super LSI”, “ultra LSI”depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSIs, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor inwhich connections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSIs as aresult of the development of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application in biotechnology isalso possible.

The present application is based on Japanese Patent Application No.2005-288300, filed on Sep. 30, 2005, the entire content of which isexpressly incorporated by reference herein.

INDUSTRIAL APPLICABILITY

The radio transmitting apparatus and radio transmission method accordingto the present invention is applicable to a mobile station apparatus,base station apparatus and the like in a mobile communication system.

1. A communication method for use by a base station, comprising:transmitting, to a mobile station, (i) information for determining afirst coding rate, and (ii) offset information; receiving, from themobile station, a first type of data coded with the first coding ratethat is determined by the mobile station based on the information fordetermining the first coding rate; and receiving, from the mobilestation, a second type of data coded with a second coding rate that iscalculated by the mobile station based on (i) the information fordetermining the first coding rate and (ii) the offset information, thecalculating the second coding rate comprising adjusting the first codingrate based on the offset information.
 2. The method of claim 1 whereinthe first type of data comprises user data and the second type of datacomprises control information.
 3. The method of claim 1 comprising usinga look-up table.
 4. The method of claim 1 wherein the information fordetermining the first coding rate and the offset information areincluded in a modulation and coding scheme (MCS) signal transmitted bythe base station.
 5. A base station, comprising: a transmitting unitconfigured to transmit, to a mobile station, (i) information fordetermining a first coding rate, and (ii) offset information; and areceiving unit configured to receive, from the mobile station, a firsttype of data coded with the first coding rate that is determined by themobile station based on the information for determining the first codingrate, and a second type of data coded with a second coding rate that iscalculated by the mobile station based on (i) the information fordetermining the first coding rate and (ii) the offset information, thecalculating the second coding rate comprising adjusting the first codingrate based on the offset information.
 6. The base station of claim 5wherein the first type of data comprises user data and the second typeof data comprises control information.
 7. The base station of claim 5,comprising: a look-up table.
 8. The base station of claim 5 wherein theinformation for determining the first coding rate and the offsetinformation are included in a modulation and coding scheme (MCS) signal.9. A base station, comprising: a transmitting unit configured totransmit information for determining a first coding rate, and offsetinformation; and a receiving unit configured to: receive and decode afirst type of data coded with the first coding rate; and receive anddecode a second type of data coded with a second coding rate, whereinthe second coding rate is based on the first coding rate adjusted basedon the offset information.
 10. The base station of claim 9 wherein thefirst type of data comprises user data and the second type of datacomprises control information.
 11. The base station of claim 9,comprising: a look-up table.
 12. The base station of claim 9 wherein theinformation for determining the first coding rate and the offsetinformation are included in a modulation and coding scheme (MCS) signaltransmitted by the base station.
 13. The base station of claim 12,comprising: a look-up table, wherein the base station is configured togenerate the MCS signal using the look-up table.
 14. A non-transitorycomputer-readable medium whose contents configure a first communicationapparatus to communicate with a second communication apparatus byperforming a method, the method comprising: transmitting, by the firstcommunication apparatus to the second communication apparatus,information for determining a first coding rate and offset information;decoding, by the first communication apparatus and based on the firstcoding rate, data of a first type received from the second communicationapparatus and coded with the first coding rate; and decoding, by thefirst communication apparatus and based on a second coding rate, data ofa second type received from the second communication apparatus and codedwith the second coding rate, wherein the second coding rate is based onthe first coding rate adjusted based on the offset information.
 15. Thenon-transitory computer-readable medium of claim 14 wherein the firsttype of data comprises user data and the second type of data comprisescontrol information.
 16. The non-transitory computer-readable medium ofclaim 14, wherein the method comprises using a look-up table.
 17. Thenon-transitory computer-readable medium of claim 14 wherein theinformation for determining the first coding rate and the offsetinformation are included in a modulation and coding scheme (MCS) signaltransmitted by the first communication apparatus.
 18. The non-transitorycomputer-readable medium of claim 17 wherein the first communicationapparatus uses a look-up table to generate the MCS signal.
 19. Thenon-transitory computer-readable medium of claim 14 wherein the firstcommunication apparatus comprises a base station and the secondcommunication apparatus comprises a mobile station.